China is a country mainly based on thermal power generation. Coal combustion in thermal power plants causes severe atmospheric pollution: emission of SO2 of electric systems takes up more than 45% of the national emission of SO2. In order to respond to a call for reducing the mission of SO2 of China, most of the thermal power plants are equipped with a desulfurization system, where a limestone gypsum wet flue gas desulfurization (Limestone Gypsum Wet Flue Gas Desulfurization) technology becomes a first choice of a desulfurization process of the thermal power plants because of advantages such as high desulfurization efficiency, stable operation, a chip absorbent raw material, and recyclable byproduct materials. However, certain desulfurization wastewater is generated when the system operates. Treatment for the desulfurization wastewater becomes critical for accomplishing a zero discharge of wastewater of the thermal power plants because ingredients of the desulfurization wastewater are special, complex, and strongly corrosive.
At present, main methods for treating the desulfurization wastewater are pretreatment (triple-box softening clarification and pipe filtering); condensation and reduction (concentration by evaporation of MED and MVR, membrane concentration MF/RO, UF/RO, UF/NF, UF/RO/ED, UF/RO/FO, and UF/RO/MD); and solidification treatment (natural evaporation and crystallization, an evaporation pond, mechanical atomization and evaporation, and flue atomizing evaporation). The technology of flue atomizing evaporation is predominant in aspects such as an investment cost, a running cost, and a floor surface. However, as an industrial adjustment in China, a load rate of a thermal power plant is low, and a smoke discharging temperature is reduced. When the load is low, a smoke discharging temperature of an air preheater is within 110° C., affecting an evaporation effect of a liquid droplet (the smoke temperature being lower than an acid dew point has a strong corrosivity to a device) and an evaporation capacity. In another aspect, a forced popularization of low-low temperature (GGH) shortens an effective length of a flue which may be used by the flue evaporation, and a narrow space limits a water evaporation quantity; and a complex structure of the flue and an internal support rod add risks of getting dusty, incrusted, and corroded, having great influences on original equipment (such as the flue and a dust collector) of a power plant.